Marine Biology

, Volume 103, Issue 2, pp 253–259

Competition for inorganic carbon between photosynthesis and calcification in the symbiont-bearing foraminifer Amphistegina lobifera

  • B. ter Kuile
  • J. Erez
  • E. Padan

DOI: 10.1007/BF00543355

Cite this article as:
ter Kuile, B., Erez, J. & Padan, E. Mar. Biol. (1989) 103: 253. doi:10.1007/BF00543355


The processes of photosynthesis and calcification in the symbiont-bearing foraminifer Amphistegina lobifera compete for inorganic carbon (Ci). This conclusion is based on kinetic carbon uptake experiments performed in spring 1987 on specimens from the Gulf of Eilat, Red Sea, that were preincubated in Ci-free seawater in order to empty their internal carbon pools. Photosynthetic rates at 0.8 and 2.2 mM external Ci concentration were initially high and decreased with time while calcification rates started low and increased with time. At Ci=4.2 mM, when inward diffusion of Ci is not rate limiting, both rates were high from the beginning of the experiment. Calcification rates of specimens incubated with 3(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), to inhibit photosynthesis, were high and constant at all Ci levels. Addition of carbonic anhydrase (CA) to the medium, which catalyses the conversion of HCO3-to CO2, stimulated photosynthesis but inhibited calcification, probably because it caused the collapse of the internal Ci pool for calcification. Attempts to measure natural CA activity in the foraminifera gave negative results. These observations cannot be explained by models featuring mutual enhancement of photosynthesis and calcification, but instead suggest competition for Ci between these two processes.

Copyright information

© Springer-Verlag 1989

Authors and Affiliations

  • B. ter Kuile
    • 1
  • J. Erez
    • 2
  • E. Padan
    • 3
  1. 1.The Interuniversity Institute of EilatThe Hebrew University of JerusalemEilatIsrael
  2. 2.Department of GeologyThe Hebrew University of JerusalemJerusalemIsrael
  3. 3.The Division of Microbial and Molecular Ecology, Institute of Life SciencesThe Hebrew University of JerusalemJerusalemIsrael
  4. 4.Unit for Tropical DiseasesThe International Institute for Cellular and Molecular PathologyBrusselsBelgium

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